Water-soluble polymers contained within the discrete phase of water-in-oil emulsions, the so-called inverse emulsions, are a common article of commerce. Practically every company which sells to the industries in which high molecular weight water-soluble polymers are used markets the polymers in the form of these emulsions.
When first introduced to the marketplace, these emulsions consisted of a hydrocarbon continuous phase, the discrete phase containing the highly concentrated high molecular weight polymer and water (usually about 50% polymer and 50% water), and the emulsifying surfactant, which was of the oil-soluble, low HLB type. These emulsions were relatively stable, and required an "activator", added to the water of dilution, in order to invert in a reasonable time. (In order to be used, it is necessary to have the high molecular weight polymer in dilute aqueous solution). Although it has been claimed that the emulsions would invert without the use of an activator, it was found that this took an impractically long time, or impractically high agitation rates, to be commercially useful. In some cases, inversion without the activator did not occur at all. The activator is a water-soluble, high HLB-type surfactant. However, many users of these emulsions found that it was inconvenient to have a "two-barrel" treatment program, consisting of the emulsion in one drum, and the activator in the second drum. Each of these required its own concentration for use, with two separate feed rates that needed to be carefully monitored, i.e., if too little activator was used, the emulsion did not invert properly, and if too much activator was fed, the emulsion inverted too rapidly, which would cause feeding problems and gelation.
In recent years, the so-called "self-inverting" emulsions have been introduced. In these inverse emulsions, the inverting surfactant is contained in the emulsion package itself, thus only one drum is required for use. Because of the convenience of this approach, practically all inverse emulsions sold today are of the self-inverting type. However, these products are not without their own problems. The principal deficiency of these emulsions is their instability, caused by the presence of the destabilizing inverting surfactant. This leads to a shortened shelf life. In addition, these products must be agitated before use, since some settling occurs even with short storage times. In addition, the inverting surfactant, which is the last ingredient to be added to the formulation, again to minimize stability problems, must be carefully monitored in order to avoid the same kinds of problems alluded to above for the addition of activator. It would be advantageous if the inverse emulsion did not require a separate step of adding an inverting surfactant.
It is thus an object of this invention to provide a self-inverting water soluble polymer contained within a water-in-oil emulsion.
It is a further object of this invention to provide a self-inverting water-soluble polymer contained within a water-in-oil emulsion which inverts easily and does not require an inverting surfactant.
It is still a further object of this invention to provide a self-inverting water-soluble polymer contained within a water-in-oil emulsion which polymer is used to flocculate suspended inorganic and organic matter contained primarily in aqueous systems--such as those set forth in Flesher et al., hereinafter described and incorporated herein by reference.